cable dielectric cause of artificial sound

Agree, audiophiles are often too critical with minor details, but oxidation which occurs at the surface of a conductor must be taken seriously. Electrical signal tends to travel at the surface of a conductor, NOT the center of a conductor as some may think.

It's not so bad as you portray. At audio frequencies the signal current flows through the entire cross section of the conductor, with increasing current density as you move out radially from the center. The difference between the current density at the center and that out toward the surface depends on frequency and the diameter of the conductor.

But so what? As I said previously, all the oxide layer does is effectively reduce the diameter of the conductor by a microscopic amount. This will also reduce its cross sectional area which will have the effect of moving a tad more current toward the center of the conductor and ultimately reduce the effect you're speaking of here.

In other words, the current density throughout the cross section will be very slightly more uniform than it would have been otherwise.

One example is the conductor designed by Analysis Plus, they design a conductor which is hollow in the center.

Sure, that's one approach. Or you can just use smaller diameter conductors. The smaller the diameter of the conductor, the more uniform the current distribution through its cross section will be for a given frequency.

Allowing the surface of a conductor to oxidize over time will change the character of the cable and shorten cable life.

Don't see how it would change the character of the cable in any significant way or shorten cable life. Soon as copper is exposed to the air, it soon gets a surface layer of oxidation. This layer of oxidation actually works to prevent further oxidation

Hell, I have a couple of spools of bare copper wire here that are probably going on 40 years old. Still in good shape.

Oxidation is a reason why air dielectric is not used more often.

I would disagree. But if the reason is oxidation, I'd say it's because people tend to irrationally freak out about it just because they've been told by someone that they should freak out about it

se

Several cable manufacturers are using cotton dielectric. Has anyone identified a sonic signature for cotton compared to PTFE?

Steve,
In the world of audiophile where isolation cones, cable lifters, contact enhancers are used, a oxidized conductor would not go over well. Audiophiles will pay hundreds to thousands for a pair of cable where copper used are of 5 nines to 6 nines in purity, what's the the use of buying this quality if oxidation is not controlled by the designer. Oxidation shorten the life of a cable when it sound characteristic is changed due to oxidation, yes it does sound different. I don't mean it's life is shorten because it no longer work.
Your spools of bare copper wire laying around will probaly work for another 40 years, but the quality and sound won't be the same. Keep in mind, this thread started as differences between dielectric, so people are extremely critical with the slightest change.

Rja,
Cotton dielectric sound slightly less analytical than Teflon, but the ultimate is still the geometry of the cable.
Partsconnexion is another place to buy cotton dielectric wire.

Scar

I have to throw in with Steve, and agree that surface oxidation is not necessarily something to be afraid of.
It's important to remember that most wire used in audio is annealed, and annealing takes place at high temperatures, which can cause functionally significant oxidation within seconds. However, this can be controlled somewhat by manipulating available oxygen levels and cooling times.
When considering stranded wire, such as that used in speaker wire and power cables, a small amount of surface oxidation can actually reduce the negative effects of strand interaction and eddy currents, without the higher dielectric losses seen with strand coatings.

Tim

LeVasseur Audio

Several cable manufacturers are using cotton dielectric. Has anyone identified a sonic signature for cotton compared to PTFE?

I'm not much of a "sonic signature" kind of guy, but I do prefer cotton over plastics, including PTFE. And ultimatley prefer silk over cotton.

One thing worth noting though is that the dielectric constant given for cotton, saying it's even lower than Teflon, is somewhat misleading. The figure that's given (1.3 to 1.4) is for cotton in its raw form, i.e. balls. In its textile form, i.e. woven into thread and fabric, is higher and more akin to that of silk at 2.5 to 3.5.

So for those who are obsessed with numbers, unless you string your wire through a bunch of cotton balls, you're not going to get that 1.3 to 1.4 dielectric constant.

Reference Audio Mods sells braided cotton sleeving in various sizes and vt4c.com over in Hong Kong sells braided silk sleeving (as well as cotton).

And as I mentioned previously, VH Audio sells a 28 gauge solid silver wire with a quad serve of cotton insulation (serve means it's wrapped directly around the wire rather than being a braided sleeving).

se